新制御圧延(TMCP)型50キロ級高張力鋼溶接継手部の疲労強度とその評価(その5) : セパレーション・降伏比の観点から

概要

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In order to investigate the effects of the maximum separation index (SImax.) and yield ratio (Y.R.) of steel plates on fatigue strength in welded joints of TMCP-HT50 [TMCP-manufactured 50kgf/mm^2 (500MPa)-class high tensile] steels, fatigue tests were performed. The results were summarized as follows: (1) The non-load-carrying-T-fillet welded joint of the steel plate with SImax. of 0.8 possessed 1.5 times as long fatigue crack propagation life as that with SImax. of zero. Numerous microcracks generated perpendicular to the principal fatigue crack were observed only in the plate with SImax. of 0.8. (2) On the contrary, the fatigue strength in elementary component joint with the toe of a stiffener for the steel plate with SImax. of 0.8 was not different from that with SImax. of zero. Microcracks perpendicular to the principal crack were not observed on the fatigue fracture surfaces of these specimens. (3) The effect of yield ratio on fatigue strength was not identified in the fatigue test results for the elementary component joints of steel plates with various yield ratios, which were in the range of the current ship classification. It would be desired to develop two new types of steel plates, one of which effectively generates microcracks during fatigue crack propagation, and the other of which has a further reduced yield ratio.
社団法人日本船舶海洋工学会の論文
1993-03-29